Railway signaling system



Nov. 16, 1937;

H. s YOUNG RAILWAY SIGNALING SYSTEM 4 Sheets-Sheet 1 INVENTOR HearYauny.

- Filed July 28, 1936 1155 ATTORNEY Noy. 16, 1937. H. s. YOUNG RAILWAYSIGNALING SYSTEM 4 Sheets-Sheet 2 Filed July 28, 1936 Ybung.

INVENTOR HIS ATTORNEY Nov. 16; 1937. H. s. YOUNG RAILWAY SIGNALINGSYSTEM Filed July 28, 19 56 4 Sheets-Sheet 3 INVENTOR Hen! S. 361112HLS' .AT'roRNEY N v. 16, 1937. H. s. YOUNG 2,099,508

a RAILWAY SIGNALING SYSTEM Filed July 28, 1956 4 Sheets-Sheet 4 INVENTORr Jib ATTORNEY Patented Nov. 16, 1937 I UNITED STATES PATENT, oFFicE2,099,508 RAILWAY SIGNALING SYSTEM Henry S. Young, Wilkinsburg, Paassignor to The Union Switch & Signal Company, Swissvale, Pa., acorporation of Pennsylvania,

Application July 28, 1936, Serial No. 93,030 19 Claims. (Cl. 246-46) Myinvention relates to railway signaling sysand two extreme positions.Each armature l6 terms of the type involving light signals which iscontrolled by an armature winding ll, and is are approach lighted, andis an improvement on polarized by the field from a permanent magnet thesystem disclosed in my related copending apor an electromagnet (notshown) in such manner plication, Serial No. 742,095, filed August 30,1934. that when the winding i1 is energized, the ar- Specifically, myinvention relates to signaling of mature will rotate to its left-hand orright-hand the type described wherein the signals involved extremeposition according as winding l? is then include at least twolamps andwherein the consupplied with current of normal or reverse potinuity ofthe filaments of both lamps of a signal larity, p v y. At ached to eacarmatu e are checked while such lamps are extinguished. iii to rotatetherewith are three colored roundels The present application is also animprove- G, R, and Y, which are arranged to be disposed ment on thesignaling system disclosed in a co-- in the path of a beam of lightprojected from an pending application for Letters Patent of theassociated lamp UE or LE according as the arma- United States, SerialNo. 84,498, filed by P. H, ture l6 occupies its left-hand extremeposition,

Crago on June 10, 1936, which latter application its intermediate pos to its i ht-hand'excontains claims which cover broadly certain featremeposition, e p Convenience in tures of the herein-described signalingsystem. us each p UE and LE in e d aw- I will describe several forms ofrailway signaling is S w disposed above the ass ia e nding systemsembodying my invention, and will els, but it will be readily understoodthat in then point out the novel features thereof in actual practiceeach lamp will be located directly claims. back of-the associatedroundels and will have as- In the accompanying drawings, Figs. 1A ansociatedtherewith a suitable optical system, not 1B are diagrammaticviews which, when placed wn, for P oj a beam of light from the end toend in the order named, illustrate one lampp v y C0 eCted With eacharmaf m of apparatus embodying my i nti n, ture I6 is a circuitcontroller comprising two Figs. 2 and 3 are modifications of a portionof I movable Contact fi s 8 a d 9. The movthe apparatus shown in Fig.1A, and each also able Contact finger l8 cooperates with a fixedembodying my invention, contact 20 to close a contact l82ii when theSimilar reference characters refer to similar armature l5 occupies itsleft-hand extreme p 5 p-arts in each of the several views, tion, andwith a fixed contact 2! to close a con- Referring first to Figs. 1A and1 th refer tact i82l when the armature occupies its inence characters 1and 8 designate the rails of termediate position its tand extreme astretch of railway track over which traflic nor- POSitiOII; Whilemovable Contact fi e 9 mally movesin the direction indicated by thecooperates With & fi d tact 22 to close a arrows. The rails 1 and a aredivided, by insucontact Iii-22 when the ma r upi s its lated joints 9,into a plurality of sections WX, right-hand extreme POSitiOII, d With afixed X -Y, and Y--Z Each ecti i further 11.. contact 23 to close acontact 19-23 when the vided, as here shown, into two subse ti IT,armature occupies its intermediate or its left- 2T, 3T, 4T, etc. Eachsubsection is provided with a d xt p s A s n f the typ d 4.! a trackbattery It) connected across th rail t scribed is disclosedand claimedin Letters Patent one end of the subsection and with a track relay, theUnited States granted. to designated by the reference character R with aWesley B. W S, On June 1932, for Light Si prefix the same as thereference character of the IlalS- associated subsection, connectedacross the rails For governing the signals, each section is proat theother end of the subsection. vided with a neutral signal control relayand Located adjacent the entrance end of each with a polarized signalcontrol relay designated track section is a signal each designated by aby h reference characters HR n R, p suitable distinguishing referencecharacter and tively, each with a prefix the same as the refeachincluding an upper indication unit U and erence charact'erof theassociated-signal.

a lower indication unit L. Each indication unit, For governing therelays HR and DR, each 50 as here shown, is of the type commonly knownsection is provided with two line circuits each as a Searchlight signal.Referring to signal I2, including a pair of conductors which extendtofor example, the units of that signal each comthe signal for the sectionnext in advance of the prisean armature l6 mounted to rotate betweenassociated section.

an intermediate position to which it is biased, For governing the lampsUE and LE of the 5 signals, each section is provided with an approachlighting relay designated by the reference character ER with a prefixthe same as the reference character of "the associated signal. The lampsUE and LE are controlled in such a manner as to become lighted wheneverthe associated relay ER is released, and the relays ER are controlled insuch a manner as to become released whenever the associated section orthe section next in rear becomes occupied.

Each section is provided with a suitable source of direct current andwith a suitable source of alternating current, the terminals of whichare designated by the reference characters B andC, and BX and CK,respectively.

For governing the character of the current supplied to the lamps UE andLE, each section is provided with a power-off relay designated by thereference character P0 with a prefix the same as the reference characterof the associated signal. That is, the current for the energization ofthe lamps UE and LE is supplied from the associated terminals BX and CXor from the associated terminals B and C according as the associatedrelay PO is energized or deenergized, respectively. The relays P0 aregoverned in such a manner as to be energized only when the source ofalternating current is present. The current for lighting the lamps,therefore, is normally supplied from the alternating current source butis automatically switched over to the direct current source when thealternating current is absent.

For governing the polarity of the current supplied to the relay DR forthe section next in rear, each section is provided with a pole changingrelay designated by the reference character PC with a prefix the same asthe reference character of the associated signal.

For controlling the relays PC and the current supplied for the controlof the relay DR for the section next in rear as well as for governingthe lower mechanism of the associated signal, each section is providedwith an auxiliary relay designated by the reference character LOP with aprefix the same as the reference character of the associated signal.

For at times controlling the relays LOP, each section is provided with alightout relay designated by the reference character LO with a prefixthe same as the reference character of the associated signal. Each relayL0 is connected in series with the upper lamp UE of the associatedsignal whenever the associated app-roach lighting relay ER is released.Connected across the winding of each relay L0 is an asymmetric unit 2dfor the purpose of by-passing each half wave of alternating current. Itwill be apparent, therefore, that each relay LO will become energizedwhenever the upper lamp UE of the associated signal is lighted either byalternating current or by direct current.

Each auxiliary relay LOP is provided with two energizing circuits.Referring to signal I 4, for example, relay ldLOP is normally energizedby a circuit which passes from terminal B through front point of contact25 of relay HER, filament 26 of lamp UE of signal I4, wire 27, filament28 of lamp LE of signal I4, front point of contact 29 of relay HER, backpoint of contact 30 of relay MLO, and relay I4LOP to terminal C. Whenrelay MLO is energized, however, relay MLOP is provided with anotherenergizing circuit which passes from terminal B over front'point ofcontact 3B of relay MLO and relay |4LOP to terminal C. Relay MLOP,therefore, is energized whenever the associated lamps are dark providedthe filaments of both such lamps are intact and also whenever the upperlamp of signal 54 is burning. It is understood, of course, that theresistance of relay MLOP will be of such value that the current requiredby this relay will not be sufiicient to light lamp filaments 25 and 28.

Each relay LOP is provided with control circuits similar to those justdescribed for the relay MLOP.

Associated with each section is an automatic train stopping device and acontrol relay designated by the reference characters V and VR,respectively, each with a prefix the same as the reference character ofthe associated signal. The clearing circuits for the train stoppingdevices V will become closed only when the associated relay VR isenergized so that its front contact 51 is closed. The relays VR willbecome energized only when the associated relays HR and PC are energizedprovided the associated relay DR is energized in the normal direction.It is understood, of course, that the automatic train stopping devices Vare not necessary to the operation of the system and may, therefore, beeliminated if desired.

Having thus described in general the apparatus shown in Figs. 1A and 13,I will now describe the operation of the system.

Each of the signals is controlled by the associated relays HR and DR inthe following manner: When relay HR is deenergized (see signal 15),windings ll of both the upper and lower mechanisms U and L of thatsignal are deenergized and relay EEER also is deenergized so that bothlamps UE and LE of signal it are lighted to cause the signal to displaya red light over a red light to indicate stop. The circuit for lamp UEmay be traced from terminal BX through front point of contact 311 ofrelay H'EPO, relay I5LO and asymmetric unit 24 in multiple, back pointof contact 32 of relay l5ER, filament 26, back contact 33 of relay iEER,and front point of contact 34 of relay IBPO to terminal CX. The circuitfor lamp LE may be traced from terminal BX through front point ofcontact 3! of relay l5PO, reactor 35, back point of contact 36 of relayI5ER, filament 28, back contact 33 of relay IBER, and front point ofcontact 3 3 of relay i5PO to terminal OK. The reactance of reactor 35 isapproximately equal to the reactance of relay i5LO so that the currentreceived by lamps UE and LE will be substantially uniform. Conseqently,both lamps will display an indication of substantially the sameintensity.

When relay HR is energized and relay DR is deenergized (see signal It),the upper mechanism U of that signal is energized in the reversedirection and the lower mechanism U is denergized so that, when thelamps UE and LE become lighted, signal M will display a yellow lightover a red light to indicate approach. The circuit for mechanism U maybe traced from terminal B through front contact 31 of relay MHR, backpoint of contact 33 of relay I iDR, winding ll of mechanism U, backpoint of contact 39 of relay MDR, and front contact as of relay HiI-IRto terminal C.

When relay HR is energized and relay DR also is energized in the reversedirection (see signal [3), the upper mechanism U is energized in thereverse direction and the lower mechanism L is energized in the normaldirection so that, when lamps UE and LE of signal i3 become lighted,that signal will display a yellow light over a green light to indicateapproach medium. The circuit for the upper mechanism U may be tracedfrom terminal B through front contact ll of relay I3HR, reverse polarcontact 42- 53 of relay itDR, front point of contact Aid of relay ISDR,Winding ll of mechanism 'U, front point of Contact 45 of relay I3DR,reverse polar contact le-M of relay I3DR, and front contact 48 of relayHER toterminal C. The circuit for the lower mechanism L may be tracedfrom terminal B through front contact 4! of relay I3HR, front contact atof relay EELOP, contacts 19-42 and l3-2l of mechanism U of signal it,front contact 553 of rclay I3DR, reverse polar contact 5i52 of relayI3DR, winding H of mechanism L, reverse polar contact 5354 of relayiZ-ZDR, front contact 55 of relay ifiDR, and front contact at of relayE3133 to terminal C. From the last mentioned circuit, it will be seenthat the lower mechanism L cannot be energized unless the associatedauxiliary relay LOP also is energized and then only if the associatedupper mechanismU is in a condition for the display of a yellow light.

When relay HR is energized and relay DR energized in the normaldirection (see signal 52) the upper mechanism U is energized in thenormal direction over easily traced circuits and the lower mechanism Lis deenergizecl so that, when the lamps UE and LE of signal it becomelighted, that signal will display a green light above a red light toindicate proceed.

As here shown, a train K occupies the section immediately to the rightof location Z that relay El-IR is deenergized to cause iii to displaythe stop indication and relay i iHR is energized to condition signal Mfor the display of the approach indication. The circuit for relay MHRmay be traced from terminal B at signal l5, through resistor (iii, backpoint of con tact (ii of relay iFlHR, front contact 52 of relay 6TB,front contact of relay relay MEIR, front contact E l of relay E'TRv andfront con act 85 of relay ETR to terminal C. The of resistor Bil isapproximately equal to the sistance of the associated. relay ER so thatthe energization of the relay HR for the section nextin rear ismaintained at a substantially uniform value regardless of whether therelay HR for the section in advance is. energized o-r deenergized. Thecircuit for each of the relays HR is similar to that described for therelay ifiHR except that when the relay HR for the section in advanceenergized the approach lighting relay ER for such advance section shouldbe substituted for the resistor iii Since relay i lHR is en rgized andrelay is deenergized, so that signal M is in a condi ion to display theapproach indication, relay also is energized in the reverse direction tocondition signal ii: for the display of the approach medium indication.The circuit for relay Lilli? may be traced from terminal 33 at signalit, through front cont-act 3'! of relay Mr R, front contact 56 of relayMLOP, contacts is 22 of upper mechani m U of signal back point ofcontact 5i of relay MPO, relay iiiDB, front contact 68 of relay iIiHR,back point of contact 59 of relay MPO, and front contact iii of relay ilHR to terminal C.

Since relay WEIR is energized iEPDR also is energized in the reversedirection so that signal 53 is in a condition to display the approachmedium indication, relay iiiPC is ener- .gized by a circuit which passesfrom terminal B through front contact 41 of relay ltI-IR, front contact49 of relay I3LOP, contacts 22-i9and !8Zl of upper mechanism U of signalit, front contact 5!) of relay itDR, reverse polar contact 5|52 of relayHDR, contact 2G--l3 of lower mechanism L of signal !3, relay I3PC, andfront contact 468 of relay ISHR to terminal C.

In view of the fact that signal 13 is in condition to display theapproach medium indication, that both relays Mil-IR and ESPC areenergized, and that relay I3DR is energized in the re verse direction,relay IZDR is energized in the normal direction over a circuit whichpasses from terminal B at signal i3 through front contact ii of relayLil-IR, front contact 453 of relay ESLOP, contact 22-l$ of uppermechanism U of signal 53, front point of contact H of relay iIPC, frontcontact l2 of relay EZHR, relay 123R, front point of contact E3 of relayl3PC, and front contact id of relay iSI-IR to terminal C.

Since relay i2I-IR, is energized and relay iZDR is energized in thenormal direction so that si nal I2 is in a condition to display theproceed indication, relay i2PC is energized by a circuit which passesfrom terminal B through front contact T5 of relay IZHR, front contact 16of relay I2LOP, contacts 2fl|8 and iQ-"s of upper mechanism U of signal[2, contacts 23-49 and 2ll8 of lower mechanism L of signal It, relayEZPC, and front contact 11 of relayiZI-IR.

Since signal l2 and associated apparatus is in its normal condition, theline circuit for the control of the relay DR (not shown) for the sectionnext in the rear is supplied with current in the normal direction over acircuit which includes front contact 15 of relay IZI-IR, front contact16 of relay IZLOP, contact 2fll8 of upper mechanism U of signal 12, andfront points of contacts 78 and 19 of relay MP0. The signal (not shown)for suchsection next in rear, therefore,"wil1 be in a condition todisplay the normal proceed indication.

The relays PC are provided with a slow release characteristic so thattumble-down of the signal circuits to ,the rear will be avoided when themechanisms of the associated signal are caused to. change from onecondition to another condition. For example, when the train K departsfrom the section immediately to the right of signal I5 so that signal 13will be caused to assume a condition for the display of the normalproceed indication, the circuit for relay l3PC will be momentarilyopened while contacts i8 and is of signal is are changing theirpositions. Due to the slow releasing characteristic of relay IQPC,however, front points of contacts H and E3 of relay I3PC will not becomeopened to disturb the energization of the line circuit to the rear.

The relays DR are preferably provided with a retained neutralcharacteristic to avoid a momentary display of the yellow over redindication when the associated signal is changing from the yellow overgreen indication to the green over red indication. For example, if therelays DR are provided with a retained neutral feature then, when thedirection of energization of relay l3DR is changed'from reverse tonormal to causesignal I? to assume the condition for the display of agreen light over a red light, the front points M, 45, 5t and 55 of relayI3DR, will not become opened. No change in the condition of signalmechanism U or L, therefore, takes place until polar contacts 43, 46, 5|and 54 of relay ISDR actually move. Since these contacts movesimultaneously, the upper and lower mechanisms of signal 13 are causedto change their conditions at substantially the same instant and amomentary condition for the display of a false indication is avoided.

The relays HR, are provided with a slow pickup characteristic to avoidthe possibility of the associated signal momentarily assuming acondition for the display of a false proceed indication when a short caror train moves at high speed from one section into another in advance ofthe signal. For example, if a light engine should Vacate subsection iTand enter subsection 2T at such speed as to cause relay lTR to becomeenergized before relay 2TB becomes released, then the circuit for theenergization of relay IZHR would be momentarily closed until such timeas relay 2TB. becomes released. Since the sloW pickup characteristic ofrelay EZHR, however, prevents the closing of the front contacts of thisrelay during such periods, signal l2 would be prevented from assuming afalse, less restrictive condition.

When a signal and associated apparatus occupies its normal condition asshown at signal l2, then the associated relay VR becomes energized toclose the clearing circuit for the automatic train stopping deviceassociated therewith. For example, the circuit for relay lZVR passesfrom terminal B through front contact of relay iZPC, relay I2VR, normalpolar contact 8l-54 of relay IZDR, front contact 82 of relay lZDR, andfront contact T7 of relay IZHR to terminal C. Relay l2VR, therefore, canbe energized only if the sections W-X, XY, and YZ .are unoccupied andthen only if the filaments of the lamps for the signals associated withsuch sections are intact. Each of the relays VR is controlled in amanner similar to that described for the relay IZVR.

Having thus described the operation of the signaling system, I will nowdescribe the lightout protection afforded by the apparatus embodying myinvention.

For example, I shall assume that with all apparatus in the conditionshown in the drawings, that either filament 26 or filament 28 of thelamp UE or lamp LE, respectively, of signal I4 becomes broken so thatrelay MLOP becomes released. When relay MLOP is released, the opening ofits front contact 66 will disconnect energy from relay ltDR so thatsignal l3 will be caused to assume a condition for the display of theapproach indication. When signal l3 assumes this condition, signal !2will be caused to assume the condition for the display of the approachmedium indication. Consequently, the open filament of either lamp UE orlamp LE, when such filaments are dark, will cause the next twosuccessive signals in the rear to display more restrictive indicationsthan they would ordinarily display. An engineman approaching signal l4,therefore, would receive two restrictive indications before reachingsignal i so that he would have ample time to prepare to stop at thesignal having the defective lamp.

if, for example, filament 25 of lamp UE at signal 53 should becomeburned out so that relay E3LOP becomes deenergized, then energy would bedisconnected from the lower mechanism L of that signal to cause suchmechanism to assume a condition for the display of a red light. Anapproaching train, therefore, occupying section WX would find signal 13displaying a single red li ht instead of a single green light. In otherwords, the relay LOP provides not only for the display of distinctiveindications at signals in the rear of a signal at which a lamp is burnedout but also prevents, when the upper lamp of such signal is burned out,the display of the lower green light which might be mistaken for theupper green light.

Referring next to Fig. 2, I have illustrated herein a single signal andassociated apparatus, a plurality of which when connected in a signalingsystem, will provide three-block, four-indication, signaling similar tothat just described for the apparatus shown in Figs. 1A and 15. That is,if a plurality of signals and associated apparatus similar to that shownin Fig. 2 are embodied in a system with wires 84, 8t, and 88 at theright of Fig. 2 connected to wires 85, 81, and 89 at the left of Fig. 2,the system formed thereby will provide three-block, four-indication,signaling. The principal difference between the arrangement shown inFig. 2 and that shown in Figs. 1A and 1B is that the upper and lowermechanisms of the signal are controlled directly over the line circuitswithout the use of the relays HR and DR. As will be explained more indetail hereinafter, there is also some modification in the control ofthe signal for the section next in rear and in the control of the relaysPC, VR, and ER, as well as in the control for the lower mechanism L. Thecontrol of the relays PO, LO, and LOP is identical to that described forthe apparatus shown in Figs. 1A and 1B.

The reference characters HP and DP designate repeating relays whichbecome energized only when the upper mechanism U of the signal is incondition to display ayellow light and a green light, respectively. Theeasily traced circuit for relay HP includes contacts E3Zl and l522 ofupper mechanism U, and the easily traced circuit for relay DP includescontact lS-Efi of upper mechanism U.

When the upper mechanism U is energized the reverse direction, the relayHP becomes picked up and the relay DP becomes released, so that a pathis completed for connecting lower mechanism L to wires 84 and 88. Thispath includes back contact 91 of relay DP, front contact 98 of relay HP,and front contact 99 of relay LOP.

When the signal is in condition to display the stop indication, relaysPC, HP, and DP will all become deenergized and current will be suppliedin the reverse direction over a path which includes wires and 8'! tocause the signal (not shown) next in rear to assume the condition forthe display of the approach indication. This path also includes resistor60, back point of contact so of relay DP, back point of contact a! ofrelay HP, and back points of contacts 92 and 93 of relay PC.

When the signal is in condition to display the approach indication,relay HP will become energized and current will be supplied in reversedirection over a path which includes wires 85 and 81 as well as in thenormal direction over a path which includes wires 85 and 89, so that thesignal (not shown) next in rear will assume the condition for thedisplay of the approach medium indication. The first mentioned pathincludes relay EB, front point of contact 9! of relay HP,

and back points of contacts 92 and 93 of relay PC.

The second mentioned path includes front contact 94 of relay LOP, frontcontact 95 of relay HP, and back contacts 98 and 93 of relay PC.

When the signal is in condition to display the approach mediumindication, relay PC becomes energized and current is supplied in thenormal direction over a path which includes wires 85 of contacts III andN2 of relay PC. Thes'econd mentioned path includes front contact H9 ofrelay HP and back contacts HI and I 20 of relay PC.

When relay HD is energized in the reverse direction, when wires Hi4 andIE8 (which correspond to wires I65 and m9) are energized in the normaldirection and when relay HP is energized, the upper mechanism U remainsenergized in the reverse direction and the lower mechanism L becomesenergized in the normal direction to cause the signal to display theapproach medium indication. The circuit for the lower mechanism Lincludes in addition to wires IM and I08, front contact IZI of relay HD,reverse polar contact i22l23 of relay HD, and front contact ii of relayHP.

When the signal is in condition to display the approach medium.indication, relay PC be comes energized so that current is supplied inthe normal direction over wires I05 and It! to the relay HD (not shown)for the section next in rear. The circuit for relay PC may be tracedfrom terminal B through front contact E25 of relay HP, contacts 20-48and 23-I9 of lower mechanism L, front contact I26 of relay HD, and relayPC to terminal C.

When the relay HD is energized in the normal direction, as shown in thedrawings, the upper mechanism U becomes'energized in the normaldirection so that the signal will assume the condition for the displayof the normal proceed indication. The circuit for mechanism U may betraced from terminal B through normal polar contact l2Ii I! of relayI-ID, front contact H6 of relay HD, winding I1, front'contact H5 ofrelay HD, and normal polar contact Ill- 428 of relay HD to terminal C.

When the signal is in condition to display the normal proceedindication, as shown in the contact 29 of relay ER, back point ofcontact 30 of relay LO, contact I820 of upper mechanism U, contacts 2II8and 23I9 of lower mechanism L, front contact I26 of relay HD, and relayPC to terminal C.

If either lamp filament 26 or 28 becomes burned out, when the signal andassociated apparatus is in the normal condition, then relay PC willbecome deenergized to supply current to wires Hi5 and it? in the reversedirection. If

. either lamp becomes burned out, when the signal is in condition todisplay the approach medium indication, that is, when relays HP and PCare both energized, relay HP will become deenergized so that the lowermechanism L will assume the condition for the display of the red lightand so that relay PC will become deenergized to supply current to wiresI05 and H31 in the reverse direction. If either lamp filament 26 or 28becomes burned out when the signal and associated apparatus is incondition to display the approach indication, that is, when relay PC isdeenergized and relay HP is energized, relay HP will become deenergizedto disconnect energy from wire I09. It will be seen, therefore, that ifeither filament becomes burned out when the signal is in condition todisplay one of its three proceed indications, the circuits for thecontrol of the signal (not shown) for the section next in rear will bein condition for the display of th approach indication.

If the upper filament 26 becomes burned out when the signal is incondition to display the yellow over green or approach medium.indication and when a train is approaching the signal, the relay HP willbecome released by the opening of front point of contact 30 of relay L0to I cause the lower mechanism L to display a red light.

The relay PC is provided with a slow release characteristic to avoidtumble-down of the signal circuits to the rear during periods while thecontrol of relay PC is being transferred from one circuit to anothercircuit. For example, when relay PC is being transferred from control byfront contact I25 of relay HP to control by the lamp filaments 26 and28, the front contacts III and I i2 of relay PC do not become openedsothat the energization of the line circuit to the rear is notdisturbed.

The relay HP also is provided with a slow re lease characteristic sothat the circuits controlled by this relay will not become opened duringthe time relay HP is being transferred from control by contacts I922 andI8-2I of upper mechanism U to control by contacts I8--2 of uppermechanism U.

Relay HD is preferably provided with a retained neutral characteristicso that the circuits for the control of mechanism U are not held openany longer than necessary during pole changing periods. For example, ifrelay HD is provided with this feature then, when the energization ofrelay HD is changed from the reverse direction to the normal direction,front contacts H5 and H6 of relay HD do not become opened, consequently,the winding I! of mechanism U is'without energy only during the timepolar contacts H4 and Ill move from their reverse position to theirnormal position.

Relay HD is provided with a slow pickup characteristic for the samereason relay HR shown in Figs. 1A and 1B is provided with such feature,that is, to prevent the momentary display of a less restrictiveindication while a high speed light engine is moving from one trackcircuitinto another track circuit in advance.

Relay VB, is energized only when the relay HD is energized in the normaldirection and then only if the relay PC also is energized. That is, theclearing circuit for stop V is closed only if the relays HD and PC arein condition for the normal proceed indication. The circuit for relay VRmay be traced over front contact I30 of relay HD, normal polar contactI3II32 of relay HD, front contact I33 of relay PC and relay VR to terminal C.

From the foregoing description of each of the forms of apparatusembodying my invention, it will be seen that I have shown and describedherein, lightout protection schemes as applied to three-block,four-indication, signaling systems wherein if a lamp filament becomesburned out while the signal is dark, the next two signals in the rearwill be caused to assume a condition for the display of a restrictiveindication and where in if the lamp of the upper unit of a signal becomes burned out, the lower unit of that signal will be caused to assumea condition for the dis play of a red light.

Although I have herein shown and described and 81 so that the signal(not shown) next in rear will assume the condition for the display ofthe normal proceed indication. The circuit for relay PC may be tracedfrom terminal B through contacts 20I8 and I923 of lower mechanism L,front contact I of relay LOP, and relay PC to terminal C. The pathincluding wires 85 and 81 also includes relay ER, and front points ofcontacts 93 and 02 of relay PC.

When the signal is in condition to display the normal proceedindication, relay DP becomes energized over its previously mentionedcircuit.

and the relay PC remains in its energized condition to supply current inthe normal direction to wires 85 and 87. This circuit for relay PC maybe traced from terminal B through front contact fill of relay DP,contacts Iii-2i and I9-23 of lower mechanism L, front contact E00 ofrelay LOP, and relay PC to terminal C.

When the signal and associated apparatus are in condition for thedisplay of the normal pro ceed indication, relay VR will becomeenergized over a circuit which passes from terminal B through frontcontact I02 of relay LOP, front contact I03 of relay DP, and relay VR totermi nal C.

If either filament 25 or 28 of lamps UE and LE, respectively, becomesopened, relay LOP, of course, will be released. The opening of frontcontact I00 of relay LOP will release relay PC so that current will besupplied in the reverse direction to wires 85 and 81, the opening offront contact 94 will prevent the energization of wire 89, the openingof front contact 09 of relay LOP will prevent the energization of lowermechanism L, and the opening of front contact I02 of relay LOP willrelease relay VR. Therefore, if either filament becomes opened whileextinguished, the signal (not shown) for the section next in rear willbe caused to assume the condition for the display of a yellow over andlight, the lower mechanism of the signal with which such lamps areassociated will be caused, if not already in such condition, to assume acondition for the display of a red light, and the clearing circuit forthe automatic train stopping device associated with such signal, if notalready opened, will become opened.

If the relay LOP becomes released while the signal is in condition todisplay the normal proceed indication so that relay PC becomes releasedwhile relay DP remains energized, then the circuit for the control ofthe upper mechanism of the signal (not shown) for the section next inrear will include relay ER, front point of contact 90 of relay DP, backpoint of contact SI of relay HP, back points of contacts 92 and 93 ofrelay PC, and wires 85 and 8'1.

If filament 25 of upper lamp UE is burned out, then. when a train isapproaching the signal, relay LOP will remain deenergized so that lowermechanism L will be certain to be in condition to display a red light.If, on the other hand, filament 28 of the lower lamp LE is burned out,then when an approaching train releases relay ER, the upper lamp UE willdisplay its usual indication in accordance with traffic conditions inadvance.

The relays'HP and DP are each provided with a slow releasecharacteristic so that, when the upper mechanism U is changing from thecondition to display a yellow light to the condition to display a greenlight, or vice versa, while the relay PC is deenergized. a momentaryrelease of the relay ER to cause a fiash of the signal lamps will beavoided. For example, if relay PC should become released due to thereleasing of relay LOP, then energy would be supplied to back point ofcontact 92 of relay PC over front point of contact 90 of relay DP andback point of contact 0| of relay HP. If, under this condition, theupper mechanism U should now become energized in the reverse direction,relay DP would become deenergized and relay HP would become energized.Due to the slow releasing characteristic of relay DP, however, frontpoint of contact 90 of relay DP would remain closed at least until frontpoint of contact 0| of relay HP becomes closed. Relay ER, therefore,would not become released to cause a momentary flash of the signallamps. 7

Referring now to Fig. 3, I have shown herein one signal and associatedapparatus, a plurality of which when embodied in a system with wiresI04, I06, and I08 at the right of Fig. 3 connected to wires I05, I01,and I09, respectively, at the left of Fig. 3, will function to providethreeblock, four-indication, signaling similar to that described for theapparatus shown in Figs. 1A and 1B.

The apparatus illustrated in Fig. 3 differs from that shown in Figs. 1Aand 1B principally in that, in Fig. 3, the number of line control wiresis reduced and, in Fig. 3, the relay designated by the referencecharacter HD replaces the relays HR and DR shown in Figs. 1A and 1B. Aswill be explained more in detail hereinafter, the relay LOP iseliminated and its functions performed by the relays HP and PC. Thecontrol for the relays ER and VB is similar to that shown in Figs. 1Aand 1B and the control for the relays PO and L0 is identical to thatshown in Figs. 1A and 1B.

When relay HD becomes deenergized so that the signal will display thestop indication, relay PC becomes deenergized so that the relay I-ID(not shown) for the section next in rear becomes energized in thereverse direction over a path which includes resistor 60, back point ofcontact IIO of relay I-ID, back points of contacts III and H2 of relayPC, and wires I05 and I01.

When relay I-ID becomes energized in the reverse direction, the uppermechanism U becomes energized in the reverse direction to cause thesignal to display the approach indication. The circuit for uppermechanism U may be traced from terminal B through reverse polar contactlI3-I I4 of relay HD, front contact II5 of relay HD, winding I! ofmechanism U, front contact II6 of relay HD, and reverse polar contactIl|-I I8 of relay HD to terminal C.

When the upper mechanism U is energized in the reverse direction, relayI-IP becomes energized. The circuit for. relay HP may be traced fromterminal B through front point of contact 25 of relay ER, filament 25,wire 2'3, filament 28, front point of contact 20 of relay ER, back pointof contact 30 of relay LO, contacts I82I and I922 of upper mechanism U,and relay HP to terminal C.

When both relays HP and HD are energized and relay PC is deenergized,the relay HD (not shown) for the section next in rear is energized inthe reverse direction over a path which includes wires, I05 and I0! andthe lower mechanism of the signal (not shown) for the section next inrear becomes energized in the normal direction over a path whichincludes wires I05 and I053. The first mentioned path also includesrelay ER, front point of'contact I ID of relay HD, and back points onlythree forms of apparatus embodying my invention, it is understood thatvarious changes and modifications may be made therein within the scopeof the appended claims without departing from the spirit and scope of myinvention.

Having thus described my invention, what I claim is:

1. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section controlled by traffic conditionsin advance and including a pair of lamps, means effective when the rearsection is occupied to light both said lamps to cause said signal todisplay an indication, a signal for the rear section, and

leans effective if the filament of either lamp is broken when bothsections are unoccupied to cause the signal for the rear section toassume a condition for displaying a more restrictive indication thansuch signal would be in condition for if the filaments were intact.

2. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section controlled by traffic conditionsin advance and including a pair of lamps, means effective when the rearsection is'occupied to light both said lamps to cause said signal todisplay an indication, a signal for the rear section, and means forcontrolling the signal for the rear section when both sections areunoccupied including a circuit which is then completed if and only ifthe filament of each lamp is intact.

3. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section controlled by traffic conditionsin advance and including a pair of lamps, means effective when the rearsection is occupied to light both said lamps to cause said signal todisplay an indication, a signal for the rear section, and meanscontrolled in part by the filaments of both lamps effective when eitherfilament is broken and both sections are unoccupied to condition thesignal for the rear section for the display of a restrictive indication.

4. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section controlled by trafiic conditionsin advance and including a pair of lamps, means effective when the rearsection is occupied to light both said lamps to cause said signal todisplay an indication, a signal for the rear section, and a relay forcontrolling the signal for the rear section when both sections areunoccupied, said relay being then connected in series with the filamentof each lamp.

5. In combination, a forward section and a rear,

section of railway track, a signal for the forward section governed bytrafiic conditions in advance and including a pair of lamps, means forlighting said lamps when the rear section becomes occupied, a signal forthe rear section governed by traffic conditions in advance, and meansgoverned in part by the filaments of both lamps and effective if thefilament of either lamp becomes broken while both sections areunoccupied to cause the signal for the rear section to assume the samecondition that it would assume if the forward section were occupied andthe rear section unoccupied.

. 6. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section governed by traffic conditionsin advance and including a pair of lamps, means for l hting both lampsif either section becomes occupied, a signal for the rear section, andmeans for governing said signal for the rear section including a relaywhich is connected in a series circuit with the filaments of both lampsat all times except when either section is occupied, said relay having asufficiently high resistance so that when the circuit for the relay isclosed both lamps which are connected in series therewith will remainextinguished.

7. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section governed by traffic conditionsin advance and including a pair of lamps, a normally enersized approachlighting relay which becomes deenergized when the rear section isoccupied, a circuit for each lamp each including a back contact of saidapproach lighting relay, a lightout relay connected in series with thefilament for one of said lamps when said approach lighting relay isde-energized, an auxiliary relay, a circuit for said auxiliary relayincluding the filaments of both lamps in series as well as a frontcontact of said approach lighting relay and a back contact of saidlighto'ut relay, another circuit for said auxiliary relay including afront contact of said lightout relay, and a signal for the rear sectiongoverned by said auxiliary relay when both sections are unoccupied.

8. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section including a first indicationunit and a second indication unit, each said unit including a mechanismand a lamp cooperating therewith to provide a purality of differentindications, means governing said mechanisms in accordance with trafficconditions in advance of the signal, means for supplying operatingcurrent 'to both lamps when the rear section is occupied, a relay, meansfor energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp associated withthe first unit is intact when lighted, a pole changing relay governed bysaid first mentioned relay, and a signal for the rear section governedby said pole changing relay.

9. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section including a first indicationunit and a second indication unit, each said unit including a mechanismand a lamp cooperating therewith to provide a plurality of dificrentindications, means governing said mechanisms in accordance with trafficconditions in advance of the signal, means for supplying operatingcurrent to both lamps when the rear section is occupied, a relay, meansfor energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp assooiatcd withthe first unit is intact when lighted, and a traffic governing deviceassociated with said signal governed by said relay.

10. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section including a first indicationunit and a second indication unit, each said unit including a mechanismand a lamp cooperating therewith to provide a plurality of differentindications, means governing said mechanisms in accordance with trafficconditions in advance of the signal, means for supplying operatingcurrent to both lamps when the rear section is occupied, a relay, meansfor energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp associated withthe first unit is intact when lighted, a train stopping device for theforward seca relay eifective when energized to close a clearing circuitfor said device, and a circuit for said last m ntioned relay including afront contact of said first mentioned relay.

11. In combination, a forward section and a ear section of railwaytrack, a signal for the forward section including a first indicationunit and a second indication unit, each said unit including a mechanismand a lamp cooperating therewith to provide a plurality of differentindications, means governing said mechanisms'in accordance with trafficconditions in advance of the signal, means for supplying operatingcurrent to both lamps when the rear section is occupied, a relay, meansfor energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp associated withthe first unit is intact when lighted, a train stopping device for theforward section, a relay effective when energized to close a clearingcircuit for said device, and means governed by traffic conditions inadvance of said device for energizing said last mentioned relay providedsaid first mentioned relay is energized.

12. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section comprising a first mechanism anda second mechanism each including a lamp cooperating therewith toprovide a plurality of indications, means for supplying operating.current to both lamps of said signal when the rear section is occupied,a relay, means for energizing said relay provided the filaments of bothlamps are intact when operating current is disconnected therefrom, meansfor energizing said relay provided the filament of the lamp associatedwith the first mechanism is intact when lighted, means for governingsaid first mechanism in accordance with traffic conditions in advance ofthe signal, and means including said relay for governing said secondmechanism in accordance with traflic conditions in advance of thesignal.

13. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section comprising a first mechanism anda second mechanism each including a lamp cooperating therewith toprovide a plurality of indicators, means for supplying operating currentto both lamps of said signal when the rear section is occupied, a relay,means for energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp associated withthe first mechanism is intact when lighted, means for governing saidfirst mechanism in accordance with trafiic conditions in advance of thesignal, and a circuit for said second mechanism including a frontcontact of said relay.

i l. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section including a first indicationunit and a second indication unit, each said unit including a mechanismand a lamp cooperating therewith to provide a plurality of differentindications, means governing said mechanisms in accordance with trafficconditions in advance of the signal, means for supplying operatingcurent to both lamps when the rear section is cocupied, a relay, meansfor energizing said relay provided the filaments of both lamps areintact when operating current is disconnected therefrom, means forenergizing said relay provided the filament of the lamp associated withthe first unit is intact when lighted, a signal for the rear section,and a circuit for said signal including a front contact of said relay.

15. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section governed by traffic conditionsin advance and including a first mechanism and a second mechanism eachprovided with a lamp capable of cooperating therewith to display aplurality of different indications, means for supplying operatingcurrent to the lamps of both mechanisms when the rearsection isoccupied, a relay, a circuit for said relay including the filaments ofboth lamps when operating current is disconnected therefrom and acontact closed only when said first mechanism is in a particularcondition, another circuit for said relay including said contact andclosed only if the filament of the lamp associated with said firstmechanism is intact when burning, a signal for the rear section, and acircuit for said signal for the rear section including a contact of saidrelay.

16. In combination, a forward section and a rear section of railwaytrack, a signal for the forward section governed by traffic conditionsin advance and including a first mechanism and a second mechanism eachprovided with a lamp capable of cooperating therewith to display aplurality of different indications, means for supplying operatingcurrent to the lamps of both mechanisms when the rear section isoccupied, a relay, a circuit for said relay including the filaments ofboth lamps when operating current is disconnected therefrom as well as acontact closed only when said first mechanism is in a particularcondition and another contact closed only when said second mechanism isin a particular condition, and a signal for the rear section governed bysaid relay.

1'7. In combination, a stretch of railway track divided into sections, asignal for each section comprising a first m chanism and a secondmechanism each responsive to the polarity of the current suppliedthereto and each mechanism including a lamp cooperating therewith toprovide a plurality of indications, means for each section for supplyingoperating current to ooth lamps of the associated signal when either thesection next in rear or the section next in advance of such signal isoccupied, a relay for each section which is energized when operatingcurrent is disconnected from the lamps of the associated signal providedthe filaments of both lamps are then intact, said relay also beingenergized whenever the lamp of the first mechanism of the associatedsignal is burning, and means for each section controlled by theassociated relay for governing the signal for the section next in rear.

18. In combination, a stretch of railway track divided into sections, asignal for each section comprising a first mechanism and a secondmechanism each responsive to the polarity of the current suppliedthereto and each mechanism including a lamp cooperating therewith toprovide a plurality of indications, means for each section for supplyingoperating current to both lamps of the associated signal when either thesection next in rear or the section next in advance of such signal isoccupied, a relay for each section which is energized whenoperatingcurrent is disconnected from the lamps of the associated signalprovided the filaments of both lamps are then intact, said relay alsobeing energized whenever the lamp of the first mechanism of theassociated signal is burning, and means for each section including theassociated relay for insuring that the signal for the section next inrear will assume a condition for the display of a restrictive indicationwhen such relay is deenergized.

19. In combination, a stretch of railway track divided into sections, asignal for each section comprising a first mechanism and a secondmechanism each responsive to the polarity of the current suppliedthereto and each mechanism including an electric lamp, each said signalbeing capable of displaying stop when the associated mechanisms are bothdeenergized, approach when the first mechanism is energized in thereverse direction and the second mechanism is deenergized, approachmedium when the first mechanism is energized in the reverse directionand the second mechanism is energized in the normal direction, andproceed when the first mechanism is energized in the normal directionand the second mechanism is deenergized; means for energizing the firstmechanism of each signal in the normal direction provided the next threesections in advance of such signal are unoccupied and in the reversedirection provided either one or two sections next in advance of suchsignal are unoccupied, means for energizing the second mechanism of eachsignal in the normal direc tion provided the two sections next inadvance of such signal are both unoccupied and the third section inadvance of such signal is occupied,

means for lighting both lamps of each signal when either the sectionnext in rear or the section next in advance of the associated signal isoccupied, means associated with each signaleffective if the filament ofeither lamp of such signal is broken and both the sections next in rearand next in advance of the signal are unoccupied to condition the twosignals next in rear of such signal for displaying more restrictiveindications.

HENRY S. YOUNG.

